Thread-measuring mechanism for sewing machines



Sept. 4, 1923. 1.467.284 E. E. FOSTER THREAD MEASURING MECHANISM FORSEWING MACHINES Filed May 28 1917 3 Sheets-Sheet 1 1 w iiygw/or M MM unpikma,

Sept. 4, 1923.

E. E. FOS TER THREAD MEASURING MECHANISM FOR SEWING MACHINES Filed May28 1917 3 Sheets-Sheet 2 Mum/0r Mk KW Sept. 4, 1923. 1,467.284 E; E.FOSTER THREQ MEASURIRG MECHANISM FOR SEWING MACHINES Filed hiay 28 19173 Sheets-Sheet 3 mvemor" WSW Patented Sept. 4, 1923.

UNITED STATES PATENT OFFICE.

EDWARD E. FOSTER, OF BEVERLY, MASSACHUSETTS, ASSIGNOR TO 0. C. BLAKE,IN- CORPORATED, OF BOSTON, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS.

THREAD-MEASURING MECHANISM FOR SEWING MACHINES.

Application filed May 28, 1917. Serial No. 171,848.

To all whom it may concern:

Be it known that I, Eownnn E. Fos'rna, a citizen of the United States,residing at Beverly, in the county of Essex and State of Massachusetts,have invented certain Improvements in Thread-Measuring Mechanisms forSewing Machines, of which the following description, in connection withthe accompanying drawings, is a'specification, like reference characterson the drawings indicating like parts 'in the several figures.

This invention relates to sewing machines and is particularly concernedwith thread measurin mechanisms for sewin machines. achines of thisclass usually are equipped with some form of mechanism for measurin offor drawing from the thread supply t e length of thread required for eachstitch, thus limitin definitely the amount of thread subjecte tothe.manipulation of the sewing instrumentalities in each cycle andthereby enabling the machine to pull up the stitches more uniformly thanotherwise would be possible. mechanisms are arranged to varyautomatically the length of thread supplied to the sewinginstrumentalities in accordance with variations in the thickness of thework. Provision usually is made also in these machines for adjusting thelength of stitch; audit is obvious that in order to secure uniformity inthe formation of the stitches, provision should be made not only forvarymg the amount of thread supplied to the sewing instrumentalities inaccordance with the thickness of the work, but also in accordance withchanges in the length of stitch. While mechanisms designed to accomplishthis object have been -proposed heretofore they have not, so far as I amaware, proved successful; and the usual arrangement has been to designthe threadmeasurin mechanism for approximately an average cngth ofstitch or to set it'by a hand adjustment and to depend upon some form ofautomatic thread measuring mecha. nism to vary the thread measurementsin accordance with changes in the thickness of the work. Accordingly, ifthe length of stitch is changed ,without making bv hand. the requiredadjustment in the thread measuring mechanism. the result will be eitherto form a tighter or looser stitch than that formerly made or to bringthe locking or Usually these intersection of the threads, if the machineis of the lock stitch type, at a different point in the work.

It obviously is desirable both to have the lock or intersection of thethreads at substantially the same relative depth in the Work at allpoints in the seam and also to have the stitches pulled up to a uniformtension so that the strain on the seam shall be uniformly distributed onthe stitches; and it is the general object of'this invention to devisean automatic thread-measuring mechanism for sew ng machines which W1 1accomplish this resu t. The invention also aims to devise a reliable andsimple form of mechanism of this character which can be advantageouslused to control the quantityof thread de ivered in response to changesin either the thickness of the work or the length of stitch in caseswhere it is necessar to provide for variations in only one of t eseconditions.

To the accomplishment of these and other objects of the invention whichwill hereinafter appear, the invention provides certain novelcombinations and arrangements of partsand details of construction, thenature of which will be readily understood from the followingdescription of the embodiment of the invention now preferred by me,

' Referring now to the accompanying drawwas:

Figure 1 is a side elevation of the more important parts of an outsolestitching machine equipped with a thread measuring mechanism embodyinthis invention;

Fig. 2 is an elevation showin the opposite side of arts of the threameasuring mechanism s own in Fig. 1;

Fig. 3 is a vertical cross sectional view on the line 3-3, Fig. 2;

Fig. 4 is a plan view, partly in horizontal cross section, showing adetail of construction of the mechanism shown in Fig. 2;

Fig. 5 is a cross sectional view, taken substantially on the line 5--5.Fig. 6. showing the mechanism for adjusting the length of stitch in themachine shown in Fig.1; and

Fig. 6 is a vertical cross sectional view on the line 6-6, Fig. 5.

The sewin or stitching machine shown in the drawings forms the subjectmatter of the patent to Blake, 1,443,724, January 30, 1922. A detaileddescription of this machine is unnecessary for the purpose of disclosingthe present invention but it may facilitate an understanding of theconstruction shown to state that the sewing instrumentalities include aneedle 2, mounted to reciprocate toward and from a work support or.

throat plate 4, and a looper 6 which presents a loop of needle thread tothe needle in position to be caught by the hook of the needle and drawnup through the work. A loop thrower 7 passes this loop of thread over astationary shuttle located above the work and a cam-operated take uplever 8 then acts on the needle thread to set the stitch. The work isclamped during the stitch-forming operation by means of a resser foot 10mounted on the lower end 0 a rod 11 which slides through the frame andis acted upon by a spring 12 to hold the presser foot 10 firmly incontact with the work. A camoperated locking mechanism is provided tolock the presser foot in its depressed or work-clamping position whilethe stitch is being made. The position of the presser foot 10 thus iscontrolled by the thickness of the work and it is locked in saidposition while the stitch-forming instrumentalities act on the work. Thevarious sewing instrumentalities are operated by cams fast on a main camshaft 14 which is driven by spiral gears enclosed in the housin 15, oneof these gears being fast on the sha t 14 and the other fast on thevertical driving shaft 16.

The shoe S (Fig. 1) is mounted on a work support, indicated in generalby the numeral 18, which operates between successive stitchformingoperations to feed the shoe step by step past the stitch-forminginstrumentalities. The work supporting and feeding mechanism shown is ofthe character disclosed in the patent to Blake, 1,430,210, September 26,1922. But, in the machine shown in the present application thehorizontal shaft 19, which operates said mechanism, is driven by anadjustable mechanlsm by means of which the length of each feedingmovement, and conse uently the length of each stitch formed, canadjusted.

This driving mechanism is enclosed in housings 20 and 21 and is bestshown in Figs. 5 and 6. Referring to these figures, it will be seen thatthe upright shaft 16 has fast thereon a cam 22 having a cam path formedtherein with driving portions and holding portions. A pin wheel 24mounted fast on a shaft 25 is provided with a series of radial pins orrolls which enter successively the path in the cam 22, so that theconstant rotary motion of the shaft 16 is, by this mechanism,transformed into an intermittent rotative movement of the shaft 25.This'me chanical movement is fully disclosed in the patent to Blake,1,241,911. October 2, 1917. Four pinions indicated respectively at 26,

27, 28 and 29 (Fig. 5) are mounted fast on the shaft 25 and runconstantly in mesh with gears indicated respectively at 30, 31, 32 and33, all loosely mounted on the 1101- low shaft 34. This shaft isconnected to the shaft 19.

The respective pairs of pinions and gears are made of different gearratios and each gear is equipped with a clutch so that, while all thegears normally rotate freely on the hollow shaft 34, any one of thegears may be made effective to drive this shaft. These clutches are allalike and consequently a description of one only is necessary. As bestshown in F ig. 6, each clutch includes a hub member 36 keyed to theshaft 34 and mounted within a recess formed in its respective gear. Twofriction shoes indicated respectively, at 37 and 38 (Fig. 6) arepivotally mounted in the hub 36 close to its periphcry and they areprovided with hook-shaped spring arms which enter slots formed inopposite sides of the shaft 34 and terminate in small knobs 40 that liejust within the bore of the shaft. By referring to Fig. 6 it will beseen that normally the gear 31 can rotate freely on the clutch hub 36-without efi'ecting a rotative movement of the clutch, but if the ends 40of the spring arms are forced outwardly they will apply sufficientpressure to the friction shoes 37 and 38 to cause them to grip theperipheral wall of the recess in the gear 31 and establish a drivingengagement between this gear and the clutch hub 36, thus transmittingthe rotative movement of the gear to the hollow shaft 34.

In order to render any one of the four gears shown effective to drivethe shaft 34. a clutch actuator is provided which consists of a plunger41 carrying a head 42 which slides in the bore of the shaft 34. Agrooved roll 44 is secured fast to the outer'end of the plunger 41 andthe groove is engaged by pins mounted in the upper arm of a bell cranklever 46 (Figs. 1 and 5) mounted fast on a shaft 48 which rocks inbearings formed in a bracket 50. The other arm of said lever is movableover a segment plate 52 and carries a spring-pressed pin secured to aknob 54, the pin bein adapted to enter any one of a series of holes 55formed in said plate. These holes are so spaced apart that when the pin54 is in any one of them the head 42 of the plunger 41 will be inengagement with one of the four pairs of the members 40; and thearrangement is such that when the lever 46 is in the position in whichit appears in Fig. 1 the pinion 26 and ear 3O ig. 5) are effective todrive the siaft 34 and consequently to operate the work feedingmechanism. This pair of gears gives the shoe its slowest feedingmovement or, in other words, produces the shortest length of stitch. Asthe lever -16 is moved to withdraw the plunger 41 from the shaft 34, the

head 42 is moved successively into engagement with the different pairsof members 40 thus increasing the speed of the feeding movement of thework and thereby increasing the length of the stitches formed.

It will now be understood that the adjustment of the lever 46 controlsthe length of stitch and that the position of the prcsser foot 10 iscontrolled by the thickness of the work. The thread measuring mechanismshown is connected with these two elements so that a change in theposition of either the presser foot 10 or the lever 46 is effective tochange the length of thread delivered by the measuring mechanism to thestitching instrumentalities.

The thread T is led from the wax pot, or other supply, through a threadlocking mechanism indicated at 56, (Fig. 2) over a pin 58 on the end ofa thread pulling lever 60, through another thread lock 62 to a roll 64,(Fig. 1) and thence over the roll on the end of the take up lever 8 tothe looper 6. The thread locks 56 and 62 are alternately actuated sothat the thread is always under the control of one of these lockingdevices. The lock 56 comprises a stationary bracket 65 and a member 66pivotally mounted in one arm of a rocker 67 so that it can tip in thesame plane in which the rocker. tips. This rocker is pinned to a short\shaft 68 supported in a stationary bearing and an arm 69 is pinned tothe o posite end of this shaft and carries a roll 0 (Fig. 2) which runson the peripheral cam face 72 of the cam 73 mounted fast on the shaft14. A

spring 74 acts on this arm 69 in a direction This member 7'6 co-operateswith an upper spring pressed thread-engaging member 7 8, having atongued portion to enter the groove of the part 76. and having its shankpositioned in a hole 79,drilled in the machine frame. A coiled spring 80encircles a reduced part of this shank and tends con-' stantly to holdthe member 78 in engagement with its co-operating thread clamping member76. The range of movement of the arm 69 and consequently of the rocker67, is such that the thread clamp 56 is opened at certain times andclosed at other times, but the thread lock 62 always remains closed, therocking of the part 67 merely being sufficient to increase or decreasethe grip of the members 76 and 78 on the thread.

The thread drawing movement of the lever 60 takes place while the clamp56 is open. This movement is produced b cam connections including a link83 whic connects the rear end of thethread ulling lever 60 with one armof a bell cran lever 84, (Fig. 1), the other arm of which carries a roll85 running in a path 86 of a cam fast on the shaft 14. This mechanismthus gives the lever 60 a stroke of fixed length.

The variation in the thread drawing action of this lever required toenable it to pull more or less thread depending upon a change in thethread requirements, caused by eithcr a change in the adjustment of thelength of stitch or a variation in the thickness of the work, isproduced by so mounting the lever 60 with reference to the thread clamps56 and 62 that more or less of its stroke may be made eflective to drawthread from the supply. For this purpose the fulcrum 82 of the threadpulling lever 60 is mounted on one arm of a bell crank lever 88 whichmoves on a fixed fulcrum 89, Fig. 2, and the other arm of the lever 88carries the fulcrum pin 90 of a'floating lever 92. A link 94, pivoted tothe lower end of the floating lever 92 at 95, connects this lever with apin 96 mounted eccentricall on one end of the rock shaft 48 on which t estitch length adjusting lever 46'is fixed. Another link 96' pivoted tothe upper end of the floating lever 92 at 97, connects this lever withone arm of a bell crank lever 98, the other arm of which is pivotallyconnected to the 'presser foot plunger 11.

It will now be understood that when the thread measuring operation-takesplace, the rocker 67 will be ti ped about the axis of the shaft 68 in acloc -wise .direction so as to open the thread lock 56 and to increasethe grip of the thread lock 62 on the thread.

he cam connections of the lever 60 then rock this lever about itsfulcrum 82 in a clock-wise direction (referring to Fig. 2) thus movingthe pin 58 upward with reference to the thread locks and causing it todraw thread from the supply through the open thread lock 56. If desiredtwo pins 99 may be positioned on the hub of the rocker 67, as shown inFigs. 2 and 6, to guide the thread as it leaves the thread lock 56 andenters the lock 62. These pins also render the thread measuring actionmore accurate. KVhen the thread drawin stroke of the lever 61) has beencompleted, t e cam path 72 permits the spring 14 to move the rocker 67in a counter clock-wise direction thus closing the thread lock 56 andreducing the grip of the lock 62 on the thread. The sewinginstrumentalities then draw the loop of thread just measured off throughthe lock 62, which acts during this 0 eration merely as a thread tensiondevice. e thread lock 56 prevents the pulling of thread directly fromthe supply after the thread measuring operation has been completed,While the thread lock 62 operates during the thread measuring operationto prevent the pin 58 from drawing thread back away from the sewinginstrumentalities.

It will be evident from an inspection of Fig. 2, thatrhanges in theposition of the floating lever92, produced by changes in the threadrequirements, act through the bell crank lever 88 to raise or lower thefulcrum 82 of the thread pulling lver 60, Consequently, whiletheactuating mechanism for this lever gives it a stroke of-fixed length,the part of this stroke that is effective to draw thread from the supplywill be determined by the osition of the fulcrum 82 since, if thisulcrum point is raised or lowered, the limits of the reciprocatingmovement of the pin 58 will be moved up or downlongitudinally of thepath of travel of the pin. Obviously, if the upper limit of thismovement is raisedwith reference to the thread-locks, the pin will drawmore thread from the supply at each thread measuring operation, and iflowered, it will draw less thread. Since theadjustment of this fulcrumis controlled by changes. in the length of stitch or in the thickness ofthe work the length of thread measured out in each cycle will vary withchanges in these conditions.

Assuming, for intance, that the parts are in the relative positions inwhich they appear in Fig. 1 and that a thicker part of the work is movedunderthe presscr-foot 10, the consequent raising of the .resser footwill act through the bell crank ever 98 and link 96' to swing thefloating lever 92 about the pivot 95 as a fulcrum, and this change inthe posi tion of the lever 92 will act through the pivot 90 and the bellcrank lever 88 toraise the fulcrum 82 of the lever 60 and thereforecause this lever to measure off a longer length of thread. Similarly ifthe stitch length adjusting lever 46 is moved to position the pin 54 inone of the upper holes in the plate 52 to increase the length of stitch,this movement will be transmitted through the link 94 to the floatinglever 92, moving the lower end of this lever forward about the pivot 97as a fulcrum. and thus acting through the bell crank lever 88 to raisethe fulcrum 82 of the thread measur ing lever 60 and increase the lengthof thread measured 0H. The increase or decrease. as the case may be, inthe length of thread measured off will, of course, be proportional tothe change in the length of stitch and thickness of the work. The threaddelivering movement of the lever 60 and pin 58 is so timed withreference to the movements of the take up mechanism and the stitchforming instrumentalities that a substantially uniform tension ismaintained on the thread between the thread measuring mechanism and thestitch forming members while a stitch is being formed. In other words,the part 58 is moved at such a speed that it delivers thread to thestitch forming instrumentalities at substantially the rate at which theyrequire it and the presence of slack thread between theseinstrumentalities and the thread measuring mechanismi thus is avoided.

This thread measuring mechanism is very simple in construction, reliablein operation and is so constructed that it is not subject to wear ordeterioration. It obviously is entirely automatic in its action and itmeasures thread very accurately. While I have herein shown and describedthe best embodiment of this invention of which I am at present aware, itis obvious that this embodiment may be departed from in many particularswithin the skill of the mechanic and the discretion of the designer,without departing from the spirit or scope of this invention.

What is claimed as new, is

1. A thread measuring mechanism for a sewing machine comprising, incombination, a single thread pulling device mounted to have a to and fromovement, mechanism for imparting said movement to said device, andmeans for automatically varying the eflective thread pulling stroke ofsaid device in accordance with changes in the length of stitch and thethickness of the work.

2. A thread measuring mechanism for a sewing machine comprising, incombination,

a thread pulling lever, mechanism for giving said lever a stroke offixed-extent, threadengaging means co-operating with said lever, andmechanism for relatively moving said lever and means automatically inresponse to changes in the length of stitch or the thickness of the workto render more or less of said stroke effective to draw thread from thesupply.

3. A thread measuring mechanism for a sewing machinev comprising, incombination, thread engaging devices mountedadjacent to each other andrelatively movable to draw thread from a supply, mechanism for producingsaid relative threaddrawing movement, means-for adjusting the length ofstitch, a member arranged to engage the work and to be moved intodifferent ositions by changes in the thickness 0 the work, andconnections between said adjusting means and said member constructed andarranged to cause a change in the length of stitch and in the thicknessof the work to effect a change in the length of thread drawn from thesupply by the relative movement of said devices.

4. A thread measuring mechanism for a sewing machine comprising, incombination, a cam actuated thread pulling device and automaticmechanism acting independently of the cam connections of said device tocontrol the thread drawing action of said device in accordance withchanges in the thread requirements for both the length of the stitch andthe thickness of the work.

5. A thread measuring mechanism for a sewing machine comprising, incombination, two thread locking devices, a thread pulling memberarranged to act on the thread between said devices, mechanism for givingsaid member a reciprocating movement of predetermined length, andmechanism for adjusting said member bodily to transfer the limits of itsreciprocating movement longitudinally of the oath of said movement.

6. A thread measuring mechanism for a sewing machine comprising, incombination, a thread pulling member, means for reciprocating saidmember, thread engaging devices co-operating with said member to enableit to draw a measured length of thread from the thread' supply, andmechanism for adjusting the thread drawing stroke of said membercomprising a lever connected with said member to adjust it and arrangedto be moved by changes in the thread requirements for both the length ofstitch and the thickness of work.

7. A thread measuring mechanism for a sewing machine comprising, incombination, a thread pulling member, means for reciprocating saidmember, thread engaging devices co-operating with said member to enableit to draw a measured length of thread from the thread supply, andmechanism for adjusting the thread drawing stroke of said membercomprising a floating lever arranged to ad ust said member andconnections whereby said lever is given an adjusting movement by achange either in the length of stitch or in the thickness of the work.

8. A thread measuring mechanism for a sewing machine comprising, incombination, a thread pulling member, means for reciprocating saidmember, thread locking devices co-operating with said member to enableit to draw a measured length of thread from the thread supply, mechanismfor adjusting the thread drawing stroke of said member in accordancewith changes in the thickness of the work and the length of the stitchand mechanism operatin in timed relationship to the movements 0 saidmember to actuate said locking devices alternately.

9. In a sewing machine, the combination with mechanism for adjusting thelength of stitch and a device mounted for engagement with the work andarranged to be moved into different positions by changes in thethickness of the work, of a lever, means connecting said lever with saidmechanism and said device constructed and arranged to move the leverupon a change in the thickness of the work or in the length of stitch, athread pulling mechanism, and connections between said lever and saidthread pulling mechanism arranged to enable the lever to control thelength of thread drawn from the supply in each cycle by said threadpulling mechanism.

10. A sewing machine, having, in combination, stitch forming devices,and a single thread pulling device for drawing from the thread supplythe exact length of thread needed for the thread requirements of thestitch forming devices both for the length of the stitch and thethickness of the work.

11. A sewing machine, having, in combination, stitch forming devices,and a single thread pulling device for drawing from the thread supplythe exact length of thread needed for the thread requirements of thestitch forming devices both for the length of the stitch and thethickness of the work, and separate trains of mechanism for varying theefiective thread pulling stroke of said thread pulling device inaccordance with changes in the length of stitch and the thickness of thework, res

In testimony whereof name to this specification.

EDWARD E. FOSTER.

ctively. have signed my Certificate of Correction.

It. is hsrehy wrtified that the State of incorporation of the assigneein Lotlvrs Pam-m No. 1367.284. granted hvptvmhvr 4, 1923, upon theapplic-atimz nf' l'ldwa rd E. Fnstvr, of Beverly. B-Iassavhusvtts. fl animprovemvnt in 'lhrnud-Mvasul'in Mechanisms for Sowing ihn'hinvs." wasorroneously given as Masszu-lmst-tls; whm'oas said State shullld havehm'n giwn as New York as .shown by tho rm'nlds of assignments in thisotlivv: in theprintod spvnificution [mgr 4, lino 32. for tho misspollvdword intancn" road instrmw; same page, lim- 77. at'lvr the word [10"insert. the word rapid; and that the said Letters latvnt should he readwith thaw- LtUI'ILCliUIlS th u-in that the sauna-may conform to therecord of the was" in the Patent 0mm.

."-'rncl and S's-Med this 16th d:l nf October, A. D., 1923.

